Time-limit engine-choking device



Aug. 16, 1932. 1.. c. FRANK ET AL 1,872,268

TI IE LIMIT ENGINE CHOKING DEVICE Filed Jan. 30. 1930 2 Sheets-Shut 1 /9 r8 a z. 3

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T1235 LIMIT ENGINE CHOKING DEVlQE Filed Jan $0. 1956 2 Sheets-Sheet 2 v J I 1 11/1111 1/! II I 026, WWW l n 3 ATTORNEY Patented Au 16, 1932 um'rso STATES PATENT OFFICE LEO C. FRANK, 0F MCKEESPOBT, AND DAVID J. CONANT, OF, PITTSBURGH PENNSYL- VANIA, ASSIGNORS TO WESTINGEOUSE ELECTBIO'AND MANUFACTURING COMPANY, 7

A CORPORATION OF PENNSYLVANIA TIME-LIMIT ENGmE-GHOKING DEVICE Application filed January 30, 1930. Serial No. 424,616.

This invention relates to automatic timelimit choking devices for internal-combustion en ines.

ore particularlyythis invention relates to automatic time-limit choking devices for stationary internal-combustion engines used in connection with electricsystems and especially with electric lighting systems or plants adapted for' use in isolated places, such as country residences, farm homes, places where the attendant is partially or totally unskilled in the art of managing such plants, or in connection with power plants for airplane beacons, which are often very isolated and where the attendant, whether skilled or unskilled, merely makes periodic inspections of the plants to provide the necessary gasoline and oil.

Automatic choking-devices are known in the art but all these devices depend for their time of operation either on the ambient temperature, the temperature of the exhaust pipe, the engine block or the cooling system of the engine, or a combination of the ambient temperature andthe temperature of some engine part. When such choking devices are set in operation, a considerable. period of time elapses before the choking operation is discontinued, and, during the choking'operation, the engine is n'otaccelerated to the proper running speed. This effect is especially noticeable during cold weather.

Furthermore, during the operation of the starting device and the initial stages of engine operation, cold air is forced against the thermo-responsive element by the engine fan, and the temperature of the thermo-responsive element does not change through a sufliciently great temperature range to cause it to function and stop 'the choking operation. The engine, with the intermittent aid of .the automatic starting device, sputters along for a time, making every effort to take up the heavy load which actuated the automatic starting device. In the meantime, the protective device. usually provided, functions to prevent further automatic cranking. and the engine stops. After the protective device has functioned, the plant cannot be started before the apparatus is reset by the attendant.

The object of the invention is to provide v for choking an internal-combustion engine to supply a rich fuel mixture for a, predetermine interval of time during the starting operations, regardless of ambient temperature 0r engine temperature.

Another object of this invention is to provide an engine-choking device capable of producing a choking effect on the engine during starting which shall vary from a maximum to a minimum, to cause the feedin of a fuel mixture most suitable for quic starting under the particular temperature prevailing, in the combustion chambers.

A still further object of this invention is the rovision of an automatic time-limit choking device for an'internal-combustion -engine provided with an electrically controlled starting device which shall be easy of manufacture and simple in structure and which may be readily installed.

Other objects and advantages will be more Figs. 3 and a are sectional views of still further modifications of our invention.

Referring more particularly to Fig.- 1, reference character 1 designates a portion of a carburetor used with an internal combustion engine and to whichis secured, in any, convenient manner, the air-intake tube 2. At 1 the end of the intake tube remote from the carburetor, is secured a choker-valve housing 3 consisting of magnetic material. A solenoid 4, having an armature 5 is mounted within the upper portion of the housing. As shown, a stop 6 of non-magnetic material may be provided to prevent sticking of the armature when the solenoid is deenergized.

Obviously, where the design is such that the disc 10 contacts with ledge 11 before armature is in its extreme upper position, stop 6 need not be used because then an air gap between the housing 3 and armature 5 serves the purpose of stop 6. In the preferred embodiment, stop 6 is not used, and disc 10 seats firmly against ledge 11.

Secured to the lower portion of the armature, is a\,valve disc 10 which cooperates with the ledge 11 to control the flow of air through the main air-inlet openings 12 to the carburetor 1. The solenoid 4 is energized, under -bimetal strip 1 Disposed adjacent to the bimetal strip 18 and in the path of the air passing through the air-intake tube, is an electric heater 20. This heater is connected in parallel with the solenoid circuit by conductors 24 and 25.

our at the same time.

Since the solenoid and the heater are in parallel, their energization must, of necessity, oc-

The conductors 24 and 25 are suitably insulated from the tube by sleeves 22.

The bimetal strip 18 has an aperture at the free end through which extends a guide pin L or stem 14 constituting an extension of screw 13. The side-wall of the tube 2 is provided A with an auxiliary air-inlet opening within which fits a valve disc 16, having one or more relatively small apertures 17 to always admit some air to the carburetor should both valve discs 10 and 16 be sealed firmly. One of the apertures, in addition to admitting some air, serves as a guide for the valve disc on the stem 14.

Disposed intermediate the valve disc 16 "and the free end of the bimetal strip 18, and held in cooperative relation by the stem 14, is positioned a spring 15 which, in cooperation with thermostatic spring action of-the bimetal strip, urges the valve disc 16 to seating position. The screw 13 has a relatively large head whereby the spring 15 and the valve disc 16 may be readily replaced without disassembling all the parts.

The bimetal strip 18 deflects downwardly upon energization of the heater 20. thereby reducing the seating pressure of the valve disc and, in consequence, varying the effective size of the auxiliary air-inlet opening for any given engine suction. The heater is supplied with energy from a constant-voltage source, for example, the 32 volt batteries usually employed in farm-lighting plants. Intermediate the source of supply and the parallel circuit of the heater and solenoid. is positioned a thermo-electric timelimit protective cranking device (not shown) for interrupting the supply to the heater 20 and the solenoid 4.

The resistor elements of the heater have constant electrical characteristics and, since the voltage supply is constant and block 19 prevents dissipation of the heat in the strip 18, the strip 18 will, upon energization of the heater 20, be deflected a predetermined extent during a predetermined interval of time, regardless of the temperature of the atmosphere or the temperature of the engine parts.

If, at the instant of starting, the temperature of strip 18 be low, the seating pressure of disc 16 may be higher than would otherwise be the case, but such condition is desirable rather than harmful. A low initial temperature of strip 18, however, does not materially change the time constant, since the temperature of the heater 20, when energized,

is relatively high, and the bimetal strip 18 is relatively insensitive to atmospheric tern peratures.

During starting of the engine, a solenoid 4 closes oil the flow of air through the main ports 12 and, at the same instant, the heater 20 is energized. Heat passes to the strip 18 at a predetermined rate and this strip, in conjunction with the spring 15, decreases the seating pressure of valve 16 over a predetermined range during a predetermined interval of time. The amount of air admitted by valve 16 is thus varied, and that particular proportion of fuel and air most conducive to starting of the engine is ensured by the time-limit engine-choking device.

If the engine should fail to start for want of fuel'or some other cause, the protective cranking device referred to above and usually provided with automatic generating plants, would interrupt the circuit to heater 20 and solenoid 4, thus preventing injury to theseelements.

The modification shown in Fig. 2 is similar in function and, to some extent, in structure to the structure shown in Fig. 1, however, the heater is shown outside of the tube 2, and the housing 3 is provided with an auxiliary air-inlet opening 27 over which fits a valve plate 26 having one or more apertures 28. During energization of heater 20, strip 18 deflects downwardly, thus gradually increasing the effective size of opening 27.

In the modification shown in Fig. 3, the choke-valve structure shown at the right of both Figs. 1 and 2 is not used, the valve disc 16 or the valve plate 26 being made to serve the function of the choking valve 10, as well as the choking of the auxiliary opening. In

this modification, the block 119 is made of" material having very good heat conductivity,

ature than bimetal strip 18. The aeration of this modification is substantially as follows:

During starting operation, the valve disc 16 will be in closed position and the only air admitted to the carburetor will be through the apertures 17. The engine is thus choked in a desirably excessive manner during starting. During the starting period, heater 20 is energized and causes the deflection of himetal strip 18 and varies the choking effect of the valve arrangement consisting of the elements 13, 14, and 16. The same timelimit choking is thus produced as with the modifications above discussed.

When the engine starts, the heater 20 will be deener gized but bimetal strip 118 and block 119 retain suificient heat" for a short time to keep valve disc 16 seated rather loosely.

In the meantime, the engine heats up, and the heat of the ingine is readily transmitted from the tube 2, through block 119, to the bimetal strip 118, thus retaining the valve disc 16 seated very loosely or not seated at all. The flow of air to the carburetor is thus not impeded, and the same effect is accomplished as is accomplished in the modification above discussed when the disc 10. is in lowermost position.

In the modification shown in Fig. 4, the choking-valve disc 10 and its operating parts are also not used, and the remaining structure remains exactly as discussed for the modification of Fig. 1, however, an additional bimetal is mounted on the engine exhaust pipe51, and, through the, stem 52 and spider connection 53 attaching the stem to the valve, holds valve disc 116 in open position after this valve has produced its desirable time-limit choking and the engine has started. Valve disc 116, of course, might also be held open, after the engine has started, by a speed responsive device operated from the engine shaft.

While certain preferred embodiments have been illustrated and described, it will be understood that the invention is not to be limited to the specific constructions shown but that other means may be employed to ensure the desired results.

Applicants do believe they are the first to provide thermo-electric time-limit enginechoking devices. Obviously, this device may be employed in the main air-inlet opening, in which case, no auxiliary opening need be used.

Since our invention may be embodied in equivalent apparatus having different structural details, we desire that no limitations shall be imposed except as specifically defined in the appended claims.

We claim as our invention: 1. In combination with the air-intake tube of the carburetor'of an internal-combustion engine, an electro-magnetically operated choke for closing the main air-inlet'opening to the carburetor, said intake tube being rovided with an auxiliary air-inlet opening, a valve disc provided with a plurality'or' relatively small apertures and seating in" said auxiliar opening, a bimetal strip in the intake tube, a spring intermediate one end of the bimetal strip and the'valve disc to urge the valve disc toseating position by a force inversely proportional to the temperature of the bimetal strip, a screw-threaded member provided with a stem for holding the spring and valve disc in operativerelation to the bimetal strip, andan electric heater having definite electrical"characteristics and positioned adjacent to the bimetal strip to heat the air passing to the carburetonsandrange during a predetermined interval of 0 time, thereby varying the 'valve-seatingpresi Y 2. In combination with a carburetor airintake tube having a valve-controlledfair-,- inlet opening a valve disc having a plurajlity 3. In combination with the carburetor of an internal-combustion engine, an air-intake tube for the carburetor having'a main and an auxiliary air-inlet opening, an electromagnetically operated choke for completely. closing the main air-inlet opening during 5 starting of the eng'ne, a valve disc having a relatively small aperture and seating in said auxiliary opening, a temperature-re sponsive element in the-intake tube for biasing said -valve disc to seating position by a force inversely proportional to the temperature of the temperature-responsive element, and an electric heater adjacent to the temperature-responsive element and energized during the energization of said electro-magnetically operated choke to cause a variation of the valve-seating pressure over a definite range during a predetermined interval of time.

4. In combination with a carburetor airintake tube having a main air-inlet opening and an auxiliary air-inlet openin a valve. member for controlling the effective size of the auxiliary opening, a temperature-responsive element unafi'ected by atmos heric temperatures for effecting the contro v g' operation of the valve member, and an electric heater adjacent to the temperature-responsive element to cause operation of the temperature-responsive element over a predetermined range in a predetermined interval of time.

5. In combination with the air-intake tube of the carburetor oi-an internal-combustion i determined interval Of ,t1m.

engine, said intake. tube having a main and an auxiliary air-inlet opening, an electromagnetically operated choke for completely closing the mam opening during startin of the engine, an electric heater energized uring the operation of the choke, and a thermostatic element adjacent to the heater for vcontrolling the amount" of 'a1r-pass1ng through the auxiliaryopening during .a pre- 6.;In combinatiomacarburetorj for an internal-combustion engine, an air-intake-tube jfor'the' carburetor having a palr of openings,

a solenoid, an armature. operated by the so lenoid,,a valve forfclosing'joneof said openings jand. secured to thelarmature, and

' "Ithermoelectric,time limit' "means for var. ,ing'jthe'lairpassing through the other of sald 1 i s: ov a, predetermined range during ia predetermined intervalof time.

, In combination, a'carburetor for an injternal-combustion engine, an air-intake tube small opening and actuated by the temperatum-responsive element and associated with the other of said openings, whereby, upon 'energization of the solenoid and the heater, the passing of air through the first opening is. prevented and the passing of air through the second opening is varied over a predetermined range during a predetermined interval of time.

8. Incombination wit-h an internal-combustion engine, a carburetor, an air-intake tube for the carburetor having a main and an auxiliary air-inlet opening, a choke for closing the main openlng for a predetermined interval of time during starting of the engine, a temperature-responsive device secured to the intake tube, a valve for normally closing the auxiliary openin and operated by said temperature-responsive device, said valve having a relatively small aperture to admit airto the carburetor, and an electric heater having definite heating characteristics and located adjacent to the tem rature-responsive. device, whereb the e ective size of the auxiliary opening is varied over a redetermined range during a predetermined interval of time.

9. In combination with an internal-combustion engine, a carburetor, an air-intake tube for the carburetor having a main and an auxiliary air-inlet opening, a choke for completely closing the main opening for a pre etermined interval of time during startmg ofthe en e, a tem erature-responsive device secu at one en to the intake tube, a valve plate provided with at least one relatively small aperture to always admit some air to the carburetor and secured to the free endof the temperature-responsive device and fitting over the auxiliary opening, and an electric heater having definite electrical characteristics and located adjacent to the temperature-responsive device, whereby the 'efie'ctive size of the auxiliary opening is varied over. a predetermined range during a predetermined interval of time. 10; In combination with an internal-combustion engine, a carburetor, an air-intake tube "forfthe carburetor having an air-inlet opening, a 'valve'i disc havin a relatively small aperture and closingt e opening, a temperature responsive element urging the valve disc to seatin position, and an electric heater having a dei nte heating rate and disposed adjacent to the tem rature-res nsive element, whereby the efib dtive size 0 the air-inlet opening is varied over a predetermined range during a predetermined interval of time.

11. In combination with an internal-combustion engine provided with a starter, a carburetor, an air-mtake tube for the carburetor having an air-inlet opening, a valve disc having a plurality of relatively small apertures and seating in the opening, a temperatureresponsive'element urging the valve disc to seating position, and an electric heater having a definite heating rate and disposed adjacent to the temperature-responsive element and energized duringthe operation of the starter, whereby the effective size of the airinlet' opening is varied over a predetermined range during a predetermined interval of time.

12. In combination with an internal-con disc seating in the opening, a bimetal strip secured at one end and mounted in the tube,

a spring disposed intermediate the free end of the strip and the valve disc, and an electric heater energized during the operation of the starter and disposed in the tube adjacent to the bimetal strip, whereby the effective size of the opening is varied over a. predetermined range during a. predetermined interval of tlme. In testimony whereof, we have hereunto subscribed our names this 21st day of J annary, 1930.

- LEO C. FRANK.

DAVID J.- CONANT. 

